As an inverting amplifier with high driving capability and simple configuration, an inverting amplifier that uses an inverter circuit has been employed. An inverting amplifier with an inverter circuit, however, has a problem of a large variation in electrical power consumption at an operating point when an input signal is 0, caused by variations in a threshold voltage or a power supply voltage of a transistor.
In order to solve the problem, there is proposed a circuit, in which an inverter circuit for amplification is set to have a predetermined power supply voltage which is generated so that an input-output connected replica inverter has a predetermined current.
With the circuit described above, an operating point when an input signal is 0 can be fixed. The circuit, however, suffers from another issue that the operating point varies depending on change in a threshold voltage of a transistor and cannot therefore be set freely.
Further, there is proposed another circuit that has a differential pair of two transistors, in which the transistors are controlled so that a predetermined current can flow in one of the transistors regardless of a gate voltage of the other transistor. How to apply the proposed circuit to an inverting amplifier with an inverter circuit, however, has not been disclosed.
For the reasons set forth above, an existing inverting amplifier with an inverter circuit is disadvantageous in that an operating point cannot be freely set when an input signal is 0.